1. Field of the Invention
This invention relates generally to filter relief valves and especially to a unit assembly type device which may be used with various types of filters of conventional throw-away type.
2. Description of the Prior Art
A common problem with known type relief valve assemblies for use with filter elements and especially of the throw-away type is that the relief valve assembly are unduly complicated, require close assembly tolerances, and are not easily installed on assembly lines and the like with rapidity and without precise installation equipment.
Another problem with known type devices is that they use a combination relief valve and check valve structure which increase the complexity of the assembly, and also further increase manufacturing accuracies and tolerances as well as complexity of the structure.
Another problem with known type combination relief valve and check valve assemblies is that the relief valve structure per se may not readily be used with other type structures because of the integral check valve structure.
Known prior art patents which are pertinent to the disclosed invention are the patents to Paul, U.S. Pat. Nos. 3,262,567; Humbert, Jr., 3,332,554; and Humbert, Jr., 3,529,722. The Paul patent employs pressure responsive relief and regulating valves which are in the form of annular spring discs. These spring discs are made of material of high yield strength and high hardness. And are not of flexible, resilient rubber-like material. Both of the patents to Humbert, Jr. relate to combination check valve and bypass valve structure and are not of the relatively simple, minimum element arrangement of the invention disclosed herein.
A Hathaway et al U.S. Pat. No. 3,083,832 has a combination by-pass and check valve structure employing an annular sealing member together with a metal spring element for maintaining the aforesaid sealing member in proper position against valve seat structure. Again, the structure is dual purpose with the additional complexities associated therewith. Another U.S. Pat. No. 3,166,498 to Otto, Jr., employs check valve structure and is not arranged to function as a relief valve. In fact, an entirely separate relief vavle structure is required with this device. The Thorton U.S. Pat. No. 3,321,089 again combines bypass and check valve structure into a combination device. This structure is also far more complicated with the requirement of precision assembly than that of the invention disclsoed herein. The Thorton et al U.S. Pat. No. 3,567,022 is a single operating relief valve structure, but has a number of different parts including a coil spring which greatly increases the expense and assembly problems with the use of such a device.
The patent to Bumb, U.S. Pat. No. 3,984,318, granted on Oct. 5, 1976, shows a sub-assembly for use with an oil filter wherein a Belleville spring by-pass valve is in combination with a rubber antidrainback valve. Again, this structure is far more complicated and involved than that of the applicants' invention.
None of the known prior art patents have the new and unique features of the invention set forth herewithin.